Etymology Dictionary

ACHE,  a severe pain.  (E.)   α. The spelling ache is a falsified one, due to the attempt to connect it more closely with the Gk. ἄχος, which is only remotely related to it.  In old authors it is spelt ake.  'Ake, or ache, or akynge, dolor;' Prompt. Parv.   β. That the word is truly English is best seen from the fact that the M.E. aken, to ache, was a strong verb, forming its past tense as ook, ok, pl. ooke, oke, oken.  'She saide her hede oke' [better spelt ook, pron. oak]; The Knight of La Tour, ed. Wright, p. 8.  'Thauh alle my fyngres oken;'  P. Plowman, C. xx. 159.—A. S. æce, an ake, a pain; 'eal þæt sár and se æce onwæg álǽded wæs' = all the sore and the ake were taken away; Beda, 5. 3. 4 (Bosworth).   ¶ The connection with the Gk. ἄχος, obvious as it looks, is not after all very certain; for the Gk. χ is an E. g, and the right corresponding word to ἄχος is the Goth. agis, A. S. ege, mod. E. awe, as pointed out both in Fick and Curtius.  For the root of ἄχος and awe, see Anguish, Awe. [†]

ADDENDA

The A.S. word is also written ece, A.S. Leechdoms, iii. 6, l. 19.   We may go further, and derive the sb. from the strong verb acan (pt. t. óc, pp. acen), corresponding to the strong M.E. verb aken, already spoken of; we find acaþ míne eágan = my eyes ache, Ælfric's Gram., ed. Zupitza, p. 216, l. 13 (various reading in footnote).   Further, the orig. sense of acan was to drive, urge; it is cognate with Icel. aka, to drive, pt. t. ók, pp. ekinn, and with Lat. agere, to drive.   From ✔AG, to drive; see Agent.   From the same root are acre and acorn.   It follows that any connection between ache and ἅχος is impossible.